1. Field of the Invention
The present invention relates to a voltage reference circuit, and in particular to a temperature-insensitive voltage reference for an integrated circuit.
2. Description of the Related Art
The role played by voltage references in data acquisition systems and measuring instruments is critical. In hundreds of such applications, the magnitude of an unknown voltage is determined by measuring its size relative to a voltage reference.
A voltage reference therefore must produce an accurate and stable output regardless of mechanical shocks or other adverse environmental conditions.
In designing any type of voltage reference circuit, important factors such as device size, spacing, and possible mechanical stress must be considered. However, by far the most important design consideration is the thermal environment in which the voltage reference circuit is to be located.
In fact, while voltage reference circuits are intentionally configured to exhibit insensitivity to changes in ambient temperature, actual circuit design typically consumes only about 5% of the total creative effort, with management of thermal energy and supporting characterization on the chip consuming the remaining 95% of the effort. The difficulty in managing the thermal environment of the voltage reference is better appreciated when it is recognized that all of the surrounding semiconducting devices on the IC contribute a varying amount of thermal energy during operation.
Therefore, there is a need in the art for a precision voltage reference circuit which is insensitive to changes in ambient temperature.